Expelliarmus The Disarming Charm, as the name implies, enables the user to disarm another wizard or witch in a duel by forcing their wand out of their hand. With enough power behind it, the spell could also knock an opponent off their feet and send them flying.
Expecto Patronum In the magical realm of Harry Potter, there exist wraithlike creatures called Dementors that feed off the positive emotions of humans and, at worst, can siphon their very souls. The only known defense against them is the Patronus Charm, which conjures a protective spirit-like entity that, at its strongest, takes the form of an animal meant to be reflective of the caster's innermost self and deepest feelings. The spell draws strength from the user's happiest memories and is extremely difficult to perform.
Wingardium Leviosa Making things float is a standard magical power in any fantasy universe. Harry Potter is no exception, with Harry and his friends having to learn the Levitation Charm in their first year at Hogwarts.
Obliviate Memory or Forgetfulness Charm is an invaluable asset that allows wizards and witches to erase memories of things, people, and events that they do not want to remain known. However, this powerful spell could also just as easily be used for sinister intent.
Petrificus Totalus Full Body-Bind Curse spell causes temporary paralysis in whoever should fall prey to it. Under its effects, the victim's arms and legs snap together, and their petrified body collapses, completely frozen stiff for an unspecified period of time while still retaining consciousness and certain sensory function like eye movement.